Prime Minister Jacinda Ardern has condemned the "devastating one-sided loss of life" in Jerusalem after Israeli forces opened fire on Palestinian protesters who opposed the opening of the US Embassy there.

Palestinian officials say at least 52 people were killed at the border between Gaza and Israel, with 2400 more injured on Monday (local time), as thousands protested against the opening of the embassy which the US contentiously moved from Tel Aviv.

"This is the most significant violence we've seen in a number of years," Ms Ardern said on Tuesday morning.

The Prime Minister said the Ministry of Foreign Affairs and Trade (MFAT) has voiced its concerns with the Israeli Ambassador on behalf of the Government.

"It is the right of any nation to defend their border, but this is a devastating one-sided loss of life," she said.

"We would condemn the violence that has occured, and I think it's plain to see that the effects of this decision and the ramifications are wide-reaching."

President Donald Trump announced in December last year that the United States would move its embassy from Tel Aviv to Jerusalem and officially recognise Jerusalem as Israel's capital.

The Government said at the time that it would "make things difficult".

"We support a two-state solution, a peaceful resolution. We said that this would lead to a backwards step in the progress towards peace, and it has," Ms Ardern said.

National Party leader Simon Bridges said: "I think you can make the case for what America has done here, but ultimately it's hard to argue that this has made things more safe. It's certainly made things less safe, and it's worrying and troubling to see what's happening at the moment."

He said he hadn't yet seen enough detail to comment on whether Israel's use of force against Palestinians was proportionate to the protest.

"Let's call for restraint on both sides given where we're at. But there's no doubt, the US Embassy there in Jerusalem has inflamed things and it's a less safe situation than it was," Mr Bridges said on Tuesday morning.

Green Party co-leader Marama Davidson said the opening of the Embassy "has fanned flames of conflict and death" and has been used by Israel to justify violence against Palestinians.

"Jerusalem is an internationally recognised disputed territory, and the fair division of it will be a component of any enduring peace deal. The United States setting up an Embassy there purposefully undermines the Palestinian position and makes peace less likely," she said.